1 /* 2 * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "code/codeCache.hpp" 27 #include "code/nmethod.hpp" 28 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp" 29 #include "gc_implementation/g1/heapRegion.hpp" 30 #include "memory/heap.hpp" 31 #include "memory/iterator.hpp" 32 #include "oops/oop.inline.hpp" 33 #include "utilities/hashtable.inline.hpp" 34 #include "utilities/stack.inline.hpp" 35 36 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 37 38 class CodeRootSetTable : public Hashtable<nmethod*, mtGC> { 39 friend class G1CodeRootSetTest; 40 typedef HashtableEntry<nmethod*, mtGC> Entry; 41 42 static CodeRootSetTable* volatile _purge_list; 43 44 CodeRootSetTable* _purge_next; 45 46 unsigned int compute_hash(nmethod* nm) { 47 uintptr_t hash = (uintptr_t)nm; 48 return hash ^ (hash >> 7); // code heap blocks are 128byte aligned 49 } 50 51 void remove_entry(Entry* e, Entry* previous); 52 Entry* new_entry(nmethod* nm); 53 54 public: 55 CodeRootSetTable(int size) : Hashtable<nmethod*, mtGC>(size, sizeof(Entry)), _purge_next(NULL) {} 56 ~CodeRootSetTable(); 57 58 // Needs to be protected locks 59 bool add(nmethod* nm); 60 bool remove(nmethod* nm); 61 62 // Can be called without locking 63 bool contains(nmethod* nm); 64 65 int entry_size() const { return BasicHashtable<mtGC>::entry_size(); } 66 67 void copy_to(CodeRootSetTable* new_table); 68 void nmethods_do(CodeBlobClosure* blk); 69 70 template<typename CB> 71 int remove_if(CB& should_remove); 72 73 static void purge_list_append(CodeRootSetTable* tbl); 74 static void purge(); 75 76 static size_t static_mem_size() { 77 return sizeof(_purge_list); 78 } 79 80 size_t mem_size(); 81 }; 82 83 CodeRootSetTable* volatile CodeRootSetTable::_purge_list = NULL; 84 85 size_t CodeRootSetTable::mem_size() { 86 return sizeof(CodeRootSetTable) + (entry_size() * number_of_entries()) + (sizeof(HashtableBucket<mtGC>) * table_size()); 87 } 88 89 CodeRootSetTable::Entry* CodeRootSetTable::new_entry(nmethod* nm) { 90 unsigned int hash = compute_hash(nm); 91 Entry* entry = (Entry*) new_entry_free_list(); 92 if (entry == NULL) { 93 entry = (Entry*) NEW_C_HEAP_ARRAY2(char, entry_size(), mtGC, CURRENT_PC); 94 } 95 entry->set_next(NULL); 96 entry->set_hash(hash); 97 entry->set_literal(nm); 98 return entry; 99 } 100 101 void CodeRootSetTable::remove_entry(Entry* e, Entry* previous) { 102 int index = hash_to_index(e->hash()); 103 assert((e == bucket(index)) == (previous == NULL), "if e is the first entry then previous should be null"); 104 105 if (previous == NULL) { 106 set_entry(index, e->next()); 107 } else { 108 previous->set_next(e->next()); 109 } 110 free_entry(e); 111 } 112 113 CodeRootSetTable::~CodeRootSetTable() { 114 for (int index = 0; index < table_size(); ++index) { 115 for (Entry* e = bucket(index); e != NULL; ) { 116 Entry* to_remove = e; 117 // read next before freeing. 118 e = e->next(); 119 unlink_entry(to_remove); 120 FREE_C_HEAP_ARRAY(char, to_remove, mtGC); 121 } 122 } 123 assert(number_of_entries() == 0, "should have removed all entries"); 124 free_buckets(); 125 for (BasicHashtableEntry<mtGC>* e = new_entry_free_list(); e != NULL; e = new_entry_free_list()) { 126 FREE_C_HEAP_ARRAY(char, e, mtGC); 127 } 128 } 129 130 bool CodeRootSetTable::add(nmethod* nm) { 131 if (!contains(nm)) { 132 Entry* e = new_entry(nm); 133 int index = hash_to_index(e->hash()); 134 add_entry(index, e); 135 return true; 136 } 137 return false; 138 } 139 140 bool CodeRootSetTable::contains(nmethod* nm) { 141 int index = hash_to_index(compute_hash(nm)); 142 for (Entry* e = bucket(index); e != NULL; e = e->next()) { 143 if (e->literal() == nm) { 144 return true; 145 } 146 } 147 return false; 148 } 149 150 bool CodeRootSetTable::remove(nmethod* nm) { 151 int index = hash_to_index(compute_hash(nm)); 152 Entry* previous = NULL; 153 for (Entry* e = bucket(index); e != NULL; previous = e, e = e->next()) { 154 if (e->literal() == nm) { 155 remove_entry(e, previous); 156 return true; 157 } 158 } 159 return false; 160 } 161 162 void CodeRootSetTable::copy_to(CodeRootSetTable* new_table) { 163 for (int index = 0; index < table_size(); ++index) { 164 for (Entry* e = bucket(index); e != NULL; e = e->next()) { 165 new_table->add(e->literal()); 166 } 167 } 168 new_table->copy_freelist(this); 169 } 170 171 void CodeRootSetTable::nmethods_do(CodeBlobClosure* blk) { 172 for (int index = 0; index < table_size(); ++index) { 173 for (Entry* e = bucket(index); e != NULL; e = e->next()) { 174 blk->do_code_blob(e->literal()); 175 } 176 } 177 } 178 179 template<typename CB> 180 int CodeRootSetTable::remove_if(CB& should_remove) { 181 int num_removed = 0; 182 for (int index = 0; index < table_size(); ++index) { 183 Entry* previous = NULL; 184 Entry* e = bucket(index); 185 while (e != NULL) { 186 Entry* next = e->next(); 187 if (should_remove(e->literal())) { 188 remove_entry(e, previous); 189 ++num_removed; 190 } else { 191 previous = e; 192 } 193 e = next; 194 } 195 } 196 return num_removed; 197 } 198 199 G1CodeRootSet::~G1CodeRootSet() { 200 delete _table; 201 } 202 203 CodeRootSetTable* G1CodeRootSet::load_acquire_table() { 204 return (CodeRootSetTable*) OrderAccess::load_ptr_acquire(&_table); 205 } 206 207 void G1CodeRootSet::allocate_small_table() { 208 CodeRootSetTable* temp = new CodeRootSetTable(SmallSize); 209 210 OrderAccess::release_store_ptr(&_table, temp); 211 } 212 213 void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) { 214 for (;;) { 215 table->_purge_next = _purge_list; 216 CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next); 217 if (old == table->_purge_next) { 218 break; 219 } 220 } 221 } 222 223 void CodeRootSetTable::purge() { 224 CodeRootSetTable* table = _purge_list; 225 _purge_list = NULL; 226 while (table != NULL) { 227 CodeRootSetTable* to_purge = table; 228 table = table->_purge_next; 229 delete to_purge; 230 } 231 } 232 233 void G1CodeRootSet::move_to_large() { 234 CodeRootSetTable* temp = new CodeRootSetTable(LargeSize); 235 236 _table->copy_to(temp); 237 238 CodeRootSetTable::purge_list_append(_table); 239 240 OrderAccess::release_store_ptr(&_table, temp); 241 } 242 243 void G1CodeRootSet::purge() { 244 CodeRootSetTable::purge(); 245 } 246 247 size_t G1CodeRootSet::static_mem_size() { 248 return CodeRootSetTable::static_mem_size(); 249 } 250 251 void G1CodeRootSet::add(nmethod* method) { 252 bool added = false; 253 if (is_empty()) { 254 allocate_small_table(); 255 } 256 added = _table->add(method); 257 if (added) { 258 if (_length == Threshold) { 259 move_to_large(); 260 } 261 ++_length; 262 } 263 assert(_length == (size_t)_table->number_of_entries(), "sizes should match"); 264 } 265 266 bool G1CodeRootSet::remove(nmethod* method) { 267 bool removed = false; 268 if (_table != NULL) { 269 removed = _table->remove(method); 270 } 271 if (removed) { 272 _length--; 273 if (_length == 0) { 274 clear(); 275 } 276 } 277 assert((_length == 0 && _table == NULL) || 278 (_length == (size_t)_table->number_of_entries()), "sizes should match"); 279 return removed; 280 } 281 282 bool G1CodeRootSet::contains(nmethod* method) { 283 CodeRootSetTable* table = load_acquire_table(); // contains() may be called outside of lock, so ensure mem sync. 284 if (table != NULL) { 285 return table->contains(method); 286 } 287 return false; 288 } 289 290 void G1CodeRootSet::clear() { 291 delete _table; 292 _table = NULL; 293 _length = 0; 294 } 295 296 size_t G1CodeRootSet::mem_size() { 297 return sizeof(*this) + (_table != NULL ? _table->mem_size() : 0); 298 } 299 300 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const { 301 if (_table != NULL) { 302 _table->nmethods_do(blk); 303 } 304 } 305 306 class CleanCallback : public StackObj { 307 class PointsIntoHRDetectionClosure : public OopClosure { 308 HeapRegion* _hr; 309 public: 310 bool _points_into; 311 PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {} 312 313 void do_oop(narrowOop* o) { 314 do_oop_work(o); 315 } 316 317 void do_oop(oop* o) { 318 do_oop_work(o); 319 } 320 321 template <typename T> 322 void do_oop_work(T* p) { 323 if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) { 324 _points_into = true; 325 } 326 } 327 }; 328 329 PointsIntoHRDetectionClosure _detector; 330 CodeBlobToOopClosure _blobs; 331 332 public: 333 CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {} 334 335 bool operator() (nmethod* nm) { 336 _detector._points_into = false; 337 _blobs.do_code_blob(nm); 338 return !_detector._points_into; 339 } 340 }; 341 342 void G1CodeRootSet::clean(HeapRegion* owner) { 343 CleanCallback should_clean(owner); 344 if (_table != NULL) { 345 int removed = _table->remove_if(should_clean); 346 assert((size_t)removed <= _length, "impossible"); 347 _length -= removed; 348 } 349 if (_length == 0) { 350 clear(); 351 } 352 } 353 354 #ifndef PRODUCT 355 356 class G1CodeRootSetTest { 357 public: 358 static void test() { 359 { 360 G1CodeRootSet set1; 361 assert(set1.is_empty(), "Code root set must be initially empty but is not."); 362 363 assert(G1CodeRootSet::static_mem_size() == sizeof(void*), 364 err_msg("The code root set's static memory usage is incorrect, " SIZE_FORMAT " bytes", G1CodeRootSet::static_mem_size())); 365 366 set1.add((nmethod*)1); 367 assert(set1.length() == 1, err_msg("Added exactly one element, but set contains " 368 SIZE_FORMAT " elements", set1.length())); 369 370 const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1; 371 372 for (size_t i = 1; i <= num_to_add; i++) { 373 set1.add((nmethod*)1); 374 } 375 assert(set1.length() == 1, 376 err_msg("Duplicate detection should not have increased the set size but " 377 "is " SIZE_FORMAT, set1.length())); 378 379 for (size_t i = 2; i <= num_to_add; i++) { 380 set1.add((nmethod*)(uintptr_t)(i)); 381 } 382 assert(set1.length() == num_to_add, 383 err_msg("After adding in total " SIZE_FORMAT " distinct code roots, they " 384 "need to be in the set, but there are only " SIZE_FORMAT, 385 num_to_add, set1.length())); 386 387 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable"); 388 389 size_t num_popped = 0; 390 for (size_t i = 1; i <= num_to_add; i++) { 391 bool removed = set1.remove((nmethod*)i); 392 if (removed) { 393 num_popped += 1; 394 } else { 395 break; 396 } 397 } 398 assert(num_popped == num_to_add, 399 err_msg("Managed to pop " SIZE_FORMAT " code roots, but only " SIZE_FORMAT " " 400 "were added", num_popped, num_to_add)); 401 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable"); 402 403 G1CodeRootSet::purge(); 404 405 assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables"); 406 407 } 408 409 } 410 }; 411 412 void TestCodeCacheRemSet_test() { 413 G1CodeRootSetTest::test(); 414 } 415 416 #endif